Assistance with Load Flow Analysis in IEEE 34 Distribution Network on MATLAB-Simulink

Hello,

I am working with the IEEE 34-bus distribution network in MATLAB-Simulink. When running the load flow analysis after setting up the buses, I encountered the following error message:

"Warning: Matrix is close to singular or badly scaled. Results may be inaccurate. RCOND = 1.218374e-17."

Given that this is an unbalanced system, could you please advise on the potential causes of this issue?How to solve it? Additionally, are there alternative methods or tools within MATLAB-Simulink to handle load flow analysis for such systems?

Thank you for your assistance.

Best regards,

Answer 1

[Kothuri]

Hi Asi angel,

I understand that you are facing an error while running the load flow analysis of IEEE 34-bus system.

The error message “Matrix is close to singular or badly scaled” typically indicates numerical instability or issues with the system setup often due to a matrix being close to singular or badly scaled.

The error can be rectified by:

• Ensure that all bus data, line impedances, and load values are entered correctly. Small errors in data can lead to numerical instability.
• Ensure there are no lines with zero or extremely high impedance values, as these can cause singularities in the admittance matrix.
• Verify that all buses are connected and there are no isolated buses or islands within the network.
• The IEEE 34-bus system is inherently unbalanced, which can cause convergence issues in load flow analysis.
• In unbalanced systems, ensure that the load and generation data are accurately represented for each phase.
• Scale the system parameters to improve numerical stability. This can involve normalizing the values to a common base.
• Ensure that the network configuration is correct and all elements are properly connected.
• Switch to more robust load flow solvers like Newton-Raphson or Fast Decoupled methods, which are better suited for handling unbalanced systems.
• Adjust the tolerance settings for the load flow solver to allow for better convergence.
• Break down the network into smaller sections and solve them individually before combining the results.

You can refer the below file exchange link on IEEE 34-bus system and load flow analysis

https://www.mathworks.com/matlabcentral/fileexchange/123225-ieee-34-bus-distribution-feeder-phasor-simulink-model

https://www.mathworks.com/matlabcentral/fileexchange/65077-load-flow-analysis-of-6-bus-9-bus-14-bus-26-bus-30-bus-test-system-by-gs-nr-and-fast-decoupled

Alternatively, you can use

• MATLAB’s Simscape Electrical toolbox provides tools for detailed modelling and simulation of electrical power systems, including unbalanced load flow analysis.

https://www.mathworks.com/help/sps/index.html?s_tid=hc_product_card

• Use the powergui block in Simulink to perform load flow analysis. It provides options for different solvers and can handle unbalanced systems.

https://www.mathworks.com/help/sps/powersys/ref/powergui.html

• Write custom MATLAB scripts to handle specific aspects of the load flow analysis, allowing for more control over the numerical methods used.

Hope this helps!

[Asi angel]

@Kothuri

Can you explain the different methods available for solving the power flow problem? I've verified that my model matches the IEEE 34 standard, but are there any alternative approaches I could use to solve the problem at this point?

[Asi angel]

@Kothuri

The system described in the first link is the one I am currently using.

[Mohammed Rahamath Ali]

@Asi angel. You said that you were bale to match the results to IEEE bench mark values. Actually I myself am trying to match it. I was able to get the error down to 0.6% for Bus Voltage magnitude and 0.6 deg for Bus voltage angle. except for Bus 888, 890 for which the errors are 2.8% at maximum. And these two busus come after step down tranfromer. Can you please tell me about your results or better yet I can share my model (phasor). So that you can check for any discrepancies ?